William Herschel and His Sister, Caroline Herschel and Their Contributions to Astronomy
William and Caroline Herschel
Astronomers celebrated the anniversary of Sir William Herschel’s birthday on November 15. This famous musician and astronomer discovered the planet, Uranus, and made many other contributions to science. He was helped greatly by his sister, Caroline, who also became a well-known astronomer. They were even rewarded by King George III who was fascinated by science.
Born on November 15, 1738 in Hanover, Germany, the young William showed a talent for music. He became a band boy in the Hanoverian Guards, but when the French invaded Germany he volunteered for the army and decided to pursue a military career instead. Soon the artistic young musician found out that he was unsuited for the army. He deserted and escaped to England in 1751 with his father’s help when Hanover was invaded.
He worked as a music teacher and organist at the Octagon Chapel in the very fashionable city of Bath, but his true interest was astronomy. During his leisure, he started building telescopes so that he could observe the night sky in greater detail. He used reflecting telescopes – these use a mirror to reflect light, instead of a lens. He had found that refracting telescopes were clumsy to handle but the reflectors available were also too large so he made his own, improving the light reflected by the mirror by increasing the amount of copper in the alloy.
In 1781 Herschel discovered the planet Uranus, the first new planet since ancient times. He named this ‘Georgian Star’ after King George. He also discovered new moons of Uranus and two moons of Saturn.
King George was so impressed that he gave William and Caroline a house in Slough and salaries so that they could pursue their astronomical studies on a full-time basis.
He also knighted Herschel and pardoned him for desertion. He gave him a grant to build a new telescope. This eventually resulted in a huge 40-foot telescope which became a landmark. King George liked to watch the telescope being built. At one stage he remarked to the Archbishop of Canterbury, ‘Come, my Lord Bishop, I will show you the way to heaven!’ Herschel made his last observations with this telescope, including this quotation about Saturn: “Saturn was very bright and considerably well-defined… the mirror is extremely tarnished.”
Herschel made many other contributions to astronomy, including discovering more than 400 double stars and proved that some appeared to be this way because they revolved around each other, and noticing that stars formed into clusters and nebulae.
He was the first to try to measure the Sun’s motion by using nearby stars and he theorized that sunspots were holes in the sun’s atmosphere through which the cool surface of the sun could be seen.
Herschel also discovered the infrared range of sunlight. He did this passing light through a prism to see the colors of the spectrum and measuring each color with a thermometer. He realised that the temperatures became progressively higher and that red had the highest temperature. Herschel then placed the thermometer just beyond the color red where there was no visible light and found that the temperature was even higher. He realised that there was an invisible range of sunlight.
Sir William Herschel died at Slough in 1822. His son, John, also became a famous astronomer and took his father’s telescope to South Africa so that he could observe the southern skies.
Caroline decided that she would probably never get married after an attack of typhus stunted her growth. Her father taught her music and mathematics. The young Caroline showed a talent for singing
Her brother, William, asked her to join him in England when she was 22, to keep house for him. He continued to train her in singing but she became more interested in helping him with his astronomy. She assisted him with building his telescopes and painstakingly completed calculations and recorded his observations. William gave her a telescope of her own so that she could make her own observations of the night sky.
King George III was impressed with Caroline and gave her a salary of her own so that she could pursue her astronomy.
Caroline was the first woman to discover a comet and was rewarded by being made an Honorary Member of the Royal Astronomical Society. She discovered many comets - including the Herschel-Rigollet comet which appears every 155 years - and nebulae and won the Society’s Gold Medal for her catalogue of stars and nebulae.
When Caroline reached the advanced age of 97 she was visited by many scientists who were impressed with her work and the King of Prussia himself. She died aged 98, an incredible age for those days.
A minor planet called Lucretia was named after Caroline Lucretia Herschel in 1889.